Not sure if I've pinned an exact location, but there are lots of pullouts along cascade river road. Ok to camp before the park boundary. Paved road for the first 10 miles, then gravel road. Check NPS website if you're going to cascade pass trailhead. It recently reopened and it now closed again at mile 20 (to car and foot traffic) after a washout from a storm on 8/2. No cell service with T-Mobile after mile 3 or 4.